Respirator with negative pressure limiting valve



g- 13, 1968 P. SCHREIBER 7 3,396,725

RESPIRATOR WITH NEGATIVE PRESSURE LIMITING VALVE Filed Jan. 11, 1965 INVENTOR Pezer Schreiber United States A PatentO ABSTRACT OF THE DISCLOSURE A shut-off valve is mounted in the breathing tube of a respirator -for stopping the gas flow through thc tube when the gas pressure in the tube falls below a given value; I

This invention is directed to a respirator and, in particular, to a respirator for supplying life-sustaining gases to the lungs of a patient.

Conventional respirators include .those in which gas is alternately forced into and withdrawn from the :lungs of a patient. Such respirators produce a greater than or less than atmospheric pressure inthe lungs ofa patient by supplying or withdrawing a breathing gas, such as oxygen and/ or air containing oxygen. Also, such respirators are usable for administering anesthesia gases. This means that the breathing apparatus must be adjusted to serve from one operation to the other. Different methods are used for doing this. The most used is the controlling of the changeover by limiting either the pressure or volume of the gas or limiting the time of applying the gas. Some types of respirators depend upon a plurality of these methods. In the conventionally used respirators, a pressure normally occurs in the lungs of a patient which is alternately greater than and less. than atmospheric pressure. However, under certain conditions, this can be disadvantageous particularly when a lower than atmospheric pressure should not occur in the lungs.

The object of this invention is to produce a respirator in which the amount of greater than or less than atmospheric pressure in the lungs can be controlled. According to this invention, a cut off valve is inserted in the breathing tube leading from the respirator to the patient and which valve cuts off gas flow through the tube when a. pressure occurs which is below the required pressure. Thus. the advantage of this invention is in that the breathing tube is cut off when the pressure falls below a certain predetermined pressure. This may be atmospheric pressure. However, it can be above or below atmospheric pressure as is necessary under any particular condition. The respirator of this invention can thus prevent a less than atmospheric pressure as such and/or a pressure lower than a preselected pressure from occurring in the lungs of the patient.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying schematic drawings in which:

FIGURE 1 is a diagrammatic cross-sectional view through the respirator; and

FIGURE 2'is a detail view of a modification of the invention.

The respirator to which this invention is applied can be of any conventional form such as disclosed in Us. Patent No. 3,039,481, as well as any other pressure controlled breathing apparatus. For purposes of illustration in FIGURE 1, the breathing apparatus or respirator 1 includes a housing 2 communicating with an aspirator 3. Oxygen or air containing oxygen or the like is introduced through nozzle 4 in controlled quantities as supplied from "ice the pipe 5. The aspirating effect of nozzle 4 draws gas from the interior of the housing 2 through the opening 6. The outlet of the aspirator to the atmosphere is closed by 'a spring-pressed valve 7. A valve seat 8 is inserted in housing 2 adjacent valve 7. A valve head 9 is seated on valve seat 8. Valve head 9 is joined to a lever system 10 pivotallyheld in bearing 11 and extending through a membrane 12 which forms a seal against the entry of atmospheric air. This membrane enters into the control of. the pressure within housing 2. The portion 13 of the lever system 10 which lies outwardly of membrane 12 carries a soft armature 14 which is movable back and forth between two annular magnets 14a. This arrangement is used to keep the valve head 9 either closed on or open from the valve seat 8 and to prevent a fluttering of this Valve.

The respirator so far described is shown in the posi- I tion' assumed on the exhaling of air from the patients pressure. Then when a preselected less. than atmospheric pressure is reached in housing 2, the control membrane moves toward the interior of the housing and thus opens valve head 9. At this point, valve 7 closes and the gas introduced through nozzle 4 passes through the valve seat 8 into the housing. This continues until a certain pressure is reached within housing 2.

The breathing tube 15 (schematically represented) leads from housing 2 to the interior chamber 16 of a valve housing 17 forming a part of this invention. One side wall of housing 17 is formed by a thin flexible diaphragm 18 having a fiat middle portion 18a and an annular reinforcing rib 18b. This annular diaphragm 18 has its center portion secured to an extension 19 of the breathing tube leading to the lungs 20 of the patient.

Within housing 17 is an annular valve seat 21 extending from a rigid interior wall 22. When the pressure in chamber 16 is less than atmospheric pressure, then the diaphragm 18 bears against valve seat 21 to shut ott the flow of gas through the breathing tub'e.

When the pressure in chamber 16 is greater than atmospheric pressure, then the diaphragm 18 curves outwardly and opens the valve to permit gas to flow freely through the space between the valve seat 21 and the diaphragm 18. Thus the gas being exhaled from the lungs 20 passes through the valve and into housing 2. When the prevailing pressure in the system composed of the respirator 1, breathing tube 15, the valve in housing 17, and lungs 20 drops to atmospheric pressure, the diaphragm 18 is forced against valve seat 21 by atmospheric pressure. In this Way, the flow of gas between the lungs 20 and respirator 1 is interrupted. While a pressure corresponding to atmospheric pressure remains in the chamber between extension Sleeve 19 and lungs 20, the pressure in chamber 16 falls quickly due to the aspiration of gas from housing 2 until the negative pressure in housing 2 necessary for the opening of valve head 9 is reached. Then the opening of the valve head 9 changes the apparatus over to the inhaling phase. The inflowing gas increases the pressure in housing 2, breathing tube 15, and chamber 16 so that when the atmospheric pressure is exceeded in chamber 16, the diaphragm 18 is lifted off the valve seat and air flows to the lungs 20.

The pressure at which diaphragm 18 is to close against valve seat 21 can be other than that of atmospheric pressure. This is accomplished by providing springs 23 and 24 on Opposite sides of diaphragm 18. The pressure of spring 24 on diaphragm 18 is adjustable by means of the threaded nut 25 so that any desired pressure can be applied to diaphragm 18 as required. This influences the pressure at which the-respirator 1 is changed over ---'betweensaid'housing-and said breathing tube and being from inhaling to exhaling.

However, if this change-over pressure is to correspond always with atmospheric pressure, then theelements 23, 24 and 25 can be eliminated.

In the modification of FIGURE 2, the housing 17 inserted in the breathing tube 15' encloses a thin flat rubberlike tube 18 which is connected to tube 15 and to the portion 19 of the breathing tube leading to the patients lungs. Housing 17' is open to the atmosphere. When the pressure in tube 18' is greater than atmospheric pressure, then tube 18 is opened by being curved outwardly as shown by the dashed lines. On the other hand, when, during a pause in the breathing of the patient, the pressure drops to atmospheric pressure, then the sides of the tube are pressed together by atmospheric pressure and the tube functions as a valve to cut off the flowing of gas between the lungs 20 and the respirator 1. At this point, the respirator changes over as has been described for FIGURE 1.

Having now described the means by which the objec of the invention are obtained, 7 v

I claim:

1. In combination with a respirator comprising a housing, gas supply means joined to said housing, venturi means in said housing for receiving gas from said gas supply means, and valve means in said housing and communicating with said venturi means for alternately creating greater than and less than atmospheric pressures in said housing, and a breathing tube joined to said housing, the improvement comprising shut-off valve means joined exposed on one side to the atmosphere for closing the valve means when the housing pressure becomes less than atmospheric pressure.

2. In the combination of claim 1, said shut-01f valve means comprising a diaphragm valve exposed on one side to the atmOs-phrejandonthe other side to the gas pressure in said housing, and a single valve seat upon which saic'lvalve' is'seiatable. I

3.;In the combination of claim 1, said shut-oft valve means comprising a thin.fl at.rubber-like tube joined to said breathing tube.

References Cited y UNITED STATES PATENTS 1 Re. 24,193 ---8/1956 Emerson 128145.7 2,121,311 6/1938; Anderson et al.. 128145.8 2,693,180 1 1/ 1954 Galegzzi 128-142.5 2,766,753 10/1956 Voch et a1. 128-145.8 2,944,544 7/1960 Lundgren et a1. 128-110 3,039,481 6/1962 Schrieber et a1 137102 3,071,131" 1/1963 Johanisson et a1. 128-1455 3,158,152 11/1964 Bloom 128-145.5

- FOREIGN PATENTS 47,885 12/1963 Poland.

RICHARD A. GAUDET, Primary Examiner.

K. L. HOWELL, Assistant Examiner. 

